The present disclosure relates to semiconductor memory devices and, more particularly, to a storage device including a semiconductor memory device and an operating method thereof.
In general, semiconductor memory devices may be classified into volatile memory devices such as DRAMs and SRAMs and nonvolatile memory devices such as EEPROMs, FRAMs, PRAMs, RRAMs, MRAMs, and flash memories. Volatile memory devices lose their stored data when their power supplies are interrupted, while nonvolatile memory devices retain their stored data even when their power supplies are interrupted. In particular, a flash memory has advantages such as high program speed, low power consumption, and large data storage capacity. Therefore, storage devices based on a flash memory have been widely used.
Storage devices based on a flash memory include a solid state drive (SSD) that has been replacing a hard disk drive (HDD) and a memory card such as an SD card and an MMC. Since such a semiconductor memory device is fabricated with a small size, it may be embedded in a handheld electronic device. An embedded storage device may be, for example, an embedded SSD (eSSD) or an embedded MMC (eMMC). The eSSM may be used in a laptop computer, a tablet PC or an e-book, and the eMMC may be used in a mobile device.
Such a storage device includes a flash memory and a memory controller. Data is transmitted between the flash memory and the memory controller at high speed. The storage device uses a data strobe signal DQS to stably transmit the data. However, a pulse width of the data strobe signal DQS may be reduced by resistance of a signal line or the like. If the pulse width of the data strobe signal DQS becomes narrow, data may not be stably transmitted.